I added a signature to my eBook in Acrobat 11.0.03 for Mac. The eBook had about 20-30 hours of work in terms of comments. Adding a signature and saving the document on top of the original caused all the comments to be erased! This is a pretty ridiculous bug.
Does anyone know how I can restore to a previous version of this document (the versions item under the file menu is greyed out).
Sounds a serious bug, but not one I can recall seeing before. It's possible something else is happening.
What sort of comment were they?
How are you checking that the comments are erased?
Are you looking in the Comments List?
What sort of signature was it (digital or scanned)?
They were a combination of strikethroughs, attachments, highlighted text with pop-up comments, basically all the different types of markups that exist.
Look at the image to see how I know the comments were all erased.
Actually, I just clicked the green bar that says "Signature field detected" even though there is not signature field (this is a known bug in Acrobat 11.0.03). Then I just put a signature on the cover page, hoping the green bar would go away. Doing this created another copy of the document, with the same filename and the suffix "signed", and so I just rename that new file to overwrite the unsigned one, and when I went to reopen it, all my comments were gone.
You have said all along you are using Acrobat - and this is the Acrobat forum - but this is a screenshot for the free Adobe Reader. Have you been using both, or have you been using Adobe Reader all along?
Saving is not something to be done on a whim, because a signed document is often "final" and difficult or impossible to edit. It's something to do after you have finished and to make a separate copy of the file.
I think your comments were saved to the original file most likely, then the signed copy was written to the new file. I don't know where the comments went and it's alarming, but there is a reason the new file is saved with "SIGNED" on it, specifically so as not to remove your all-important working copy.
Someone else may have more insight, because it still isn't clear why the comments should have gone. However, if you don't have a backup (Time Machine in MacOS is good too) I think you have to say they are probably gone. (But don't delete the file in case someone has magic).